mode # 1278 can replace ssd ?

The factory mechanical hard drive can be replaced with s 2.5-inch form factor SSD.

However, the problem with giving us a model number is that A1278 was recycled from 2009 through 2012 on 13-inch MacBook Pros with different hardware capabilities. That affects what parts need to be ordered. For us to give you specific hardware recommendations, please do "About this Mac" from your Apple menu and tell us what that shows for your sub-model. See

Also, what macOS version is the MacBook Pro running? For best results an SSD needs macOS 10.13 High Sierra or higher.

The best action is to upgrade the existing internal drive hard drive to High Sierra BEFORE doing the SSD install. That way you can test that the computer is still working properly before throwing a hardware change into the mix.

What macOS in currently on the internal drive? That may affect instructions.

Your 2011 MacBook Pro can use the SATA 6GB SSD that will transfer data twice as fast and it would in a 2009-2010 MacBook Pro. Best Mac results here have been with Crucial MX series SSDs and OWC SSDs.